The present invention relates to a room temperature-curable polymeric composition or, more particularly, to a polyether-based polymeric composition curable at room temperature by reacting with atmospheric moisture having good workability even at a relatively low temperature.
Room temperature-curable polymeric compositions based on a polymer, in particular, having mercapto groups at the molecular chain ends are well known in the art and widely used as a so-called polysulfide-type sealing composition, for example, in building works. These room temperature-curable polymeric compositions based on a mercapto-terminated polymer have several disadvantages to be improved. For example, the consistency of the composition is greatly increased at a low temperature as is the case in outdoor works in winter so that the composition can be worked only with extreme difficulties. In addition, the room temperature-curing reaction of the composition must be accelerated by use of a strongly toxic lead-containing oxidizing agent as a curing agent to cause a serious problem on the workers' health.
Room temperature-curable polymeric compositions of which the principal polymeric constituent is a polyether terminated at both molecular chain ends each with a mercapto group have been disclosed in Japanese Patent Publication No. 52-34667. Although such a polyether-based room temperature-curable composition is somewhat improved in respect of the workability at low temperatures, the curing agent effective in such a composition is still a strongly toxic lead-containing oxidizing agent. Moreover, the compositions are usually formulated and supplied in two packages separately containing the main ingredients and the curing agent and the contents of the two packages are mixed together directly before use so that some inconvenience is unavoidable in the use thereof since, although a one-package formulation by mixing all of the necessary ingredients beforehand is known, compositions of such a one-package formulation necessarily suffer remarkable decrease in the curing velocity in comparison with the compositions of the two-package formulation.